Pseudo column level locking

Presents an optimization that can significantly enhance the concurrency provided by row-level locking in some relational DBMSs. With this optimization, the degree of concurrency obtained is comparable to that in column-level locking in some cases that are common at customer sites. Besides, this optimization does not increase the overhead of concurrency control significantly. We use the term pseudo-column-level locking (PCLL) for row-level locking enhanced with this optimization. While some versioning-based concurrency control schemes may offer better concurrency than PCLL, they are usually hard to incorporate in a relational DBMS that relies on locking for concurrency control. Our technique is simple to implement, and it has been implemented in Sybase Adaptive Server Enterprise (ASE).